The interest in using non-wood materials, such as trichomes and bamboo fibers, to make fibrous structures, for example sanitary tissue products, has recently increased in light of the continuing efforts relating to sustainability.
One non-wood material that shows promise as a replacement or partial replacement of wood pulp fibers in fibrous structures, such as sanitary tissue products, is trichomes; namely, individualized trichomes derived from plants, such as Lamb's Ear plants (Stachys byzantina). However, “clean” individualized trichomes are challenging to obtain in large amounts due to the impurities, such as stems, specks, dirt, clay, sand, and other non-trichome materials that are present with the individualized trichomes as a result of the processes for harvesting and extracting the individualized trichomes from the plants. As shown in Prior Art FIG. 1, these impurities find their way into the fibrous structures 10 made with the extracted trichomes and result in the fibrous structures 10 looking dirty and filled with specks that render the fibrous structures 10 unacceptable to consumers of the fibrous structures 10.
The known processes for extracting trichomes from plants typically utilize mechanical cutting and air sorting operations. Such operations are very costly, require high amounts of maintenance, are normally batch processes rather than continuous processes, and the extracted trichomes still contain a level of non-trichome materials, for example specks, sand, stems, that is not consumer acceptable.
Accordingly, one problem with known processes for extracting trichomes from plants is the inability to remove non-trichome materials (impurities present in the plants and/or growing environments from which the plants are harvested) cost effectively and/or in a continuous process such that the extracted trichomes contain no or a consumer acceptable level of non-trichome materials so that the extracted trichomes may ultimately be used to make consumer desirable fibrous structures for sanitary tissue products.
Extracting trichomes to sufficient purity levels (minimizing and/or eliminating the non-trichome materials within the extracted trichomes, for example to be substantially free of (less than 5% and/or less than 4% and/or less than 3% and/or less than 2% and/or less than 1% and/or less than 0.5% and/or about 0% by weight of non-trichome materials) non-trichome materials from trichome-bearing plants at commercial volumes has never been achieved prior to the present invention.
Clearly, there is a need for processes that are able to extract trichomes from plants and/or from a mixture of trichomes and non-trichome materials, such as stems, specks, dirt, clay, sand, in a cost effective, low maintenance, continuous process that results in the extracted trichomes having no or a consumer acceptable level of non-trichome materials (impurities present in the plants and/or growing environments from which the plants are harvested) such that the extracted trichomes can be used to make consumer desirable fibrous structures.